Amine promoters for hydrohalogenation

ABSTRACT

Tertiary alcohols and Type III olefins are hydrohalogenated in the presence of an amine which acts as a reaction promoter. The amine speeds up the reaction between the hydrogen chloride and tertiary alcohol or olefin without unduly increasing the amount of polymer (sludge) formation. Triethylamine and tributylamine have been found to be effective, particularly in promoting the hydrochlorination of tertiary alcohols.

[ Dec. 3, i974 I 1 AMINIE PROMOTERS FOR FOREIGN PATENTS OR APPLICATIONSHYDROHALOGENATION 632,346 11/1949 Great Britain 260/657 [75] Inventor:.Iesse K. Boggs, Seabrook, Tex. v [73] Assignee: Exxon ResearchandEngineering Primary Emmmer Danlel Homitz Company, Linden, Attorney,Agent, or Firm-Sylvester W. Brock, Jr. 2 F d: A 1 971 [2 1 l 57 ABSTRACT[21] App1'NO':171607 Tertiary alcohols and Type III ol'efins arehydrohalogenated in the presence of an amine which [52] US. Cl. 260/657,260/671 acts as a reaction promoter. The amine speeds up the [51]. Int.Cl. C07c 17/16 reaction. between the hydrogen chloride and tertiary [58]Field of Search 260/657 alcohol or olefin without unduly increasing theY i amount of polymer (sludge) formation.

[56] References Clted Triethylamine and tributylamine have beenfound toUNITED STATES PATENTS be effective, particularly in promoting the2,013,722 9/1935 W irth... .j .5 260/657 hydrochlorination o tertiarylcohols- 2,168,167 8/1939 Leuchs 260/657 2,908,725 10/1959 Butterfieldet al 260 657 12 Clams" 2 Dawmg States Patent [1 1' t I 1111 3,852,368

AMINE PROMOTERS roR HYDROHALOGENATION CROSS-REFERENCE TO RELATEDAPPLICATIONS The subject matter of this application is related to thatdescribed in my copending application Ser. No. 101,921 filed Dec. 28,I970 and entitled Selective Tertiary Alkylation of AromaticHydrocarbons? now US. Pat. No. 3,739,039.

BACKGROUND OF THE INVENTION as a Type III" olefin, and will be of thestructure:

the requisite reaction time and thereby reduce the capi- I talinvestment for commercial facilities.

As far as the present inventor is aware, the use of an amine in themanner suggested in the present application is not known to the art.However, in US. Pat. No. 3,255,265 issued to William L. Walsh on June 7,1966, a catalyst made up of the reaction product between an arylsulfonic acid and an amine was suggested for use in a similar mannerwhen preparing tertiary alkyl halides from tertiary (i.e., Type III)olefins. The Walsh patent does not disclose the use of a catalyst whichis suitable for hydrohalogenating both tertiary alcohols and tertiary(Type III) olefins, nor does he show the use of an amine alone.

Walsh states:

It is important that the amine interact with the sulfonic acid prior toexposure to reactant acids such as hydrogen chloride (since) hydrogenchloride salts are insoluble in hydrocarbon whereas sulfonic acid-aminesalts are not only quite soluble inhydrocarbon but are even more solublein aliphatic chloride, which is the reaction product." (Emphably aninert hydrocarbon solvent.

THE DRAWINGS The drawings contain two figures, as follows:

FIG. I is a graphic illustration oi the speed of the hydrochlorinationreaction as influenced by various amine promoters; and

FIG. 2 is a graphic illustration of the speed of the hydrochlorinationreaction as influenced by different combinations of amines and solvents.

DISCUSSION OF THE PRESENT INVENTION The present invention relates to theformation of ter' tiary alkyl halides. For simplicity, however, thediscussion hereinafter will be directed to the production of tertiaryalkyl chlorides, which are representatives of the reactionstobe expectedfrom all of the halogens. As will be seen, the use of an amine speeds upthe hydrochlorination reaction without unduly increasing the amount ofdimerization (or other polymerization) which may be suffered.

Tertiary alkyl chlorides of high purity are desired as reagents in thetertiary alkylation of aromatic hydro carbons as described in mycopending application Ser.

No. 101,921, now us. Pat. No. 3,739,039; As de" scribed in thatapplication, selective tertiary alkylation of aromatic nuclei results inthe production of compounds having utilityas lubricants, either as oilsor as greases. The tertiary alkyl substituted aromatic nucleus isextremely stable, since it does not have a labile benzylic hydrogenatom. In order to carry out the selective tertiary alkylation of thecopending application, how ever, it is necessary to have tertiaryalkylchlorides of high purity and without undue amounts of secondaryalkylchloride present. The present invention is useful in producing thetertiary alkyl chlorides useful in the selective tertiary alkylationreaction claimed in the above-mentioned copending application.

The present invention employs either a tertiary alcohol or a Type III(tertiary) olefin. The tertiary alcohol can be obtained by Grignardsynthesis utilizing a suitable chloride as a primary feedstoclcTheolefin which can be used as a reactant in the present inventiomcan Toobtain tertiary alcohols, thebase feedstock is a ketone or ester. Thenature of the alkyl or aryl substituents on the tertiary alcohol aredetermined by the choice of the alkyl or aryl groups in theGrignardreagent and in the ketone orester.

In the present specification, the structure of the ter tiary alcoholswill be indicated by the number of carbon atoms in R R and R Thus 1-]-2.would indicate a five-carbon 'atom tertiary alcohol, with one carbonatom in each of R, and R and 2 carbonatoms in R The fifth carbon atom isthe tertiary carbon to which R R and R are attached.

Exemplary tertiary alcohols which have been employed in the presentinvention'are shown below in Table I.

'lA IILI') l 'lurtinry Alcohols (lrignard Kutonc or usti-r Structure 1Nov souruo 3-1-5 (Purchased) 34-6 c a 1 c; A c 6 O curd-norm ()ll ll-(Jlln As can be seen from theabove table, a large variety of tertiaryalcohols can be prepared and are suitable for use in the presentprocess. The tertiary alcohols may contain from four to 40 carbon atoms,preferably from seven to 28 carbon atoms.

Type III Olefins The present process is also suitable for use in thereaction of Type III olefins with hydrogen chloride. The Type Illolefins can be obtained, as is well known to the art, by polymerizationof a-olefins:

For example, the dimer, trimer and tetramer of propylene can be used, aswell as diisobutylene and like Type and because of their availability.In general, any amine which is soluble in the reaction media will besuitable for use in the present invention, but some care must be used inselecting a solvent'which is compatiblewith the chosen amine. Forexample, n-butylamine is effective when hexane is used as a reactionsolvent, but not when carbon tetrachloride is so employed. The aminesmay contain from two to 27 carbon atoms, preferably from six to 15carbon atoms.

In FIG. I the enhancement in reaction rate by use of the amine promotersis graphically illustrated. The data for FIG. I werederived from thehydrochlorination of the 2-1-14 alcohol:

using heptane as a solvent. Note that the reaction rate (as shown by theslopes of the curves) is significantly enhancedby use of the aminepromoter. Particularly in continuous operations, where reaction times onthe order of l to 1 /2 hours may be preferred, the reaction rates willhave been sufficiently fast as to have virtually completed the reaction(since the curves become substantially flat).

By contrast, reaction without the amine promoter is essentiallystraight-line with time.

-As will be seen hereinafter, the proper choice of solvent can provideeven better enhancement of reaction rate.

Solvents Any hydrocarbon boiling within the range from about 75F. toabout 360F. and which is liquid and inert at the reaction temperatureswill be suitable as a solvent. Normal pentane, hexane, heptane andbenzene have proven to be acceptable solvents. As discussed below,carbon tetrachloride is also suitable for use with tributylamine, butnot with small amounts of nbutylamine. Other chlorinated hydrocarbonsolvents should also be suitable. Proper selection of solvent/aminepairs can be easily made by those skilled in the art by following theprocedures in the examples hereinafter given and determining thereaction speed and specificity.

It has been found that the use of benzene or carbon tetrachloride as asolvent while employing tributylamine as a promoter leads to an enhancedreaction rate which indicates the presence of synergism. Note that inthe examples later given, tributylamine and benzene or carbontetrachloride lead to 99 percent conversion at only 2 hours reactiontime, compared to 3 A. hours for tributylamine and hexane or heptane.(With no amine promoter, Example I shows that 99 percent conversion wasnot reached even at 3 A hours).

Thus, the preferred promoter-solvent system for the present inventionwill be tributylamine with benzene or carbon tetrachloride.

The interaction between amine and solvent is shown graphically in FIG.2. The curves in FIG. 2 were derived from the hydrochlorination of the3-1-14 tertiary alcohol in various solvent amine systems. The alcohol-From FIG 2 it is seen that, with carbon tetrachloride as a solvent,there is very little effect on reaction rate if n-butylamine is employedas a promoter, even when a very large excess of the amine is employed.On the other hand, tributylamine and carbon tetrachloride provide themost active system, approached closely by benzene and tributylamine.Heptane and hexane, with tributylamine, are effective solvents but donot provide the synergistic enhancementof reaction rate exhibited bycarbon tetrachloride or benzene with tributylamine.

Reaction Conditions The alcohol or olefm feedstock is preferably admixedwith a solvent and with aqueous hydrochloric acid prior to or at thetime of introduction into the reaction zone, although the aqueous HClmay be omitted if desired. The amine additive may be admixed with theliquid constituents before or after introduction thereof into thereaction zone, preferably before, and the reaction may be carried outbatchwise or continuously. In any event, the reaction mixture (drybasis) will be made up of the following components, in the proportionsshown (the total being 100 percent by weight): a. t-alcohol or Type Illolefin feedstock, from 35 to 95 weight percent b. solvent, from 0 to 70weight percent c. amine, from 0.3 to weightpercent and d. HCl, from 5 to55 weight percent dry basis.

' Water, resulting from the alcohol-HCl reaction, will also be present,along with any water added with aqueous HCl. Aqueous HCl is equivalentto dry HCl and wa ter. Where aqueous HCl is not initially added, thewater phase will ultimately become saturated with HCl, and thus HCl inthe water is included in l-lCl (dry basis). Preferably, the reactionmixture will have the following narrower range of proportions (drybasis):

a. feedstock, from 40 to weight percent b. solvent, from 20 to 50 weightpercent 7 c. amine, from 0.5 to 5 weight percent, and

d. HCl (dry basis), from 5 to 4-5 weight percent. Water will be presentas above mentioned.

To the above admixture, gaseous HCl is passed in intimate contact at arate of from 3 to 30 volumes of HCl per volume of mixture per hour,preferably from 7 to 20 v/v/hr. (expressed at standard temperature andpressure). The reaction time is measured either as the time during whichgaseous HCl is passed through a batch reactor or as the liquid residencetime in a con tinuous reactor and, as above mentioned, will generally befrom I to 5 hours.

EXAMPLES In order to illustrate the present invention, the followingexamples are given. The procedure followed in theseexamples was asfollows.

An admixture of the feedstock, the solvent (if any), the amine and 37percent aqueous HCl was formed in a 3'-neck flask and cooled to thechosen beginning temperature. The pressure in the flask was essentiallyatmospheric. Anhydrous l-lCl gas was then bubbled through the admixturefor varying lengths of time. In some cases, the HCl addition wassuspended overnight and started again the following morning. In thosecases, the time of addition is shown as two numbers separated by a plussign.

Periodically, samples were withdrawn for analysis. At the end of thereaction, the HCl addition was terminated and the reaction mixturepoured over ice. Product workup included vacuum distillation (in mostcases) and clay percolation (in some cases).

The results of these runs are shown in the following table.

hydrochlorination of 'lvrtiary Alcohols Examplenumherhfltfl l J 4 i l, 74 Tertiary alcohol no U la" Wt. charged, grants:

Alcohol Tributylarnine.

n-Butylalnine 37% Ag. IICl.. Distilled H2O Hexane ml.)

' ll eptane (80 ml.) Benlzene (80 ml.)

a2-38-10 Gil-2km 17-83-0 Tr- -0 fllJtJ-Tr 1.0 hr. l37-Ti 934-0 v7--l5-Tr13-874) 5842Z0 2.0 hrs 80-20-0 92-8-Tr J28Tr fill-J-Tr 1004M) 84-16-0 4713-0 80-20 1 1 Final 3.5 hrs 94-6-0 OJ-Tr-Tr OQ-Tr-Tr JD-Tr-Tr -0-0034-111 88-12-0 Ell-lJ-Tr c- 41 42 43 it 45 46 Example number i I 'J l()ll 12 13 14 Tertiary alcohol Calls. Clix ll 0 U 14H 22 Wt. charged,grams:

Alcohol 126. 7 126. 7 I26. 7 I21 7 l2. 7 l2) 7-TrtbutvlhifiiiillilIII:111111111. ..l. 1:.1...lL11 l 'lAllLl". ll-(ontinuctl llytlrot-hloriunliun of 'lvrlinry Alcohols n-l3ntylamine l37% Ag, IlCl Distilled IIzN. lIexano (80 ml.) lloptane (80 ml. Benzene(80 ml.)

NMR analysis (mol percent) of cliloride/nlcohol/oleiin:

v 5.0 g. Triethylamine.

d 4.0 g. Pyridine.

s 22.5 g. tetramethyl ammonium hydroxide (20% in methanol). 1 Shorthanddesignation of this t-alcohol is (2-1-14).

From the data shown in Table ll, it is seen that the addition of theamine increases the speed of reaction in the earlier stages, which wouldallow the use of a reaction time of about one hour and together withsuitable recycle streams would allow the use of facilities requiring alower capital investment. Note particularly that the amount of chlorideformed (which is shown as the first figure in the NMR analysis) isquitelow at the end of the first half hour when no amine is present. SeeExample l where only 29% chloride was formed and Example 9 where 71%chloride was formed (at higher reaction temperatures). Compare Example I(29%) with the runs at comparable temperatures such as Examples 2 andwhich show 73 and 69% chloride formed, respectively, and Examples 3 and4 which show 54 and 52% chlorides formed, respectively. On the otherhand, at the higher temperatures shown in Examples 9 through 1 4, notethat at the end of one hour the example. showing no amine (Example 9)has only 76% reaction as opposed to 80 to 85% in all of the otherinstances.

The data show that the reaction is materially speeded up by the presenceof the amine, even though as the reaction time is allowed to becomelonger; the slow reaction does catch up with the enhanced reaction, aswould be expected in these batch reactions. Note that the data show theeffectiveness of several solvents, particularly hexane, heptane andbenzene. The carbon tetrachloride solvent is not as good when used inconjunction with n-butylamine as are the other solvents (see Examples68), but (along with benzene see Example 4) is a preferred solvent whenusing tributylamine (see Example 5). Examples l0, l3 and 14 show theeffectiveness of amines other than tributylamine and nbutylamine.Example 10 shows the effectiveness of triethylamine, Example 13 showsthe effectiveness of pyridine, and Example 14 shows the effectiveness oftetra methylammonium hydroxide.

From the data above discussed it is therefore seen that the presentinvention is effective in increasing the speed of reaction.

g The following examples show that olefins and alcohols derived fromcyclic hydrocarbons can be treated according ,to thepresent invention.

EXAMPLE 15 drocarbon, purchased treated as follows.

Apparatus used included a 2-liter flask equipped with reflux, bubbler,magnetic stirrer, thermometer and dropping tube. The flask was kept inan ice bath. Five hundred grams (3.2 moles) of l-n-butylcylohexanol, 1mole (101 g) of triethylamine, and 390 grams of npentane were charged tothe flask. Five moles (500 g) of 37% aqueous HCl were addedthrough thedropping tube. The mixture was chilled sufficiently to keep thetemperature below about 20 C., and gaseous HCl was bubbled through themixture. Sodium chloride was added to saturate the water layer as thereaction proceeded. After five hours, the reaction was stopped, and thehydrocarbon phase washed three times with 200 ml of saturated NaClsolution. The yield of percolated, stripped product was 538 grams or96.4% yield.

A similar run, using ether instead of n-pentane and using no amine,resulted in a percolated yield of 495 grams or only 88.8% yield, eventhough gaseous HCl l-n-butylcyclohexanol was 'was added over a period of8+ hours.

EXAMPLE 16 In order to illustrate the present invention as used inhydrochlorinating olefins, the following example is given. Equipmentsimilar to Example 15 was employed. To the flask were added one-fourthmole (25 g) of triethylamine, 60 g of 37% aqueous HCl, and /2 mole (49g) of 3-ethyl-2-pentene. The contents of the flask were cooled to 5C.and HCl gas was bubbled into the flask.

After 1 /2 hours, the reaction was terminated and the contentsof theflask poured over ice-salt and washed. The yield was 41 grams of3-chloro-3-me thylpentene product and only 1 gram of polymer (bottoms).

In a similar run, using glacial acetic acid as a reaction medium andwith no amine added, after 5 hours of HCl addition only 31 grams ofchloride product were obtained, while 6 grams of polymer bottoms wereformed, even though essentially the same amount (48g) of3-ethyl-2-pentane was used as a feedstock.

EXAMPLES 17-30,

In order to show that the present invention does not result in unduepolymer formation, the following examples are given. These runs weremade inessentially the same manner as in Examples 1-14. The results areset out below in Table lll.

TABLE III Sludge Formation Solvent Temperature Example Alkyl and/orTime, lnitial/ Bottoms,

No. Structure Amine Hrs. Final C. Wt,

17 2-2-2 OH Ether 2 4.5 3/18 1.1

18 2-2-2 OH None 1 (Aq. HCl) 74/85 2.5

19 2-2-2 OH nC -TEA 1.7 25/50 2 20 2-2-2 OH nC -TEA /22 Insignificant 212-2-2 Acetic Acid 3 5/10 16.2

22 2-2-2 TEA 2.5 5 2.4

23 l l-2 MeOH-TEA 6.9 -40l-29 Insignificant 24 Diisobutylene MeOH-TEA7.8 40 Insignificant 25 22-4 OH nC -TEA 5.8 15/20 Insignificant 26 3-145OH Cy-TEA 4.4 15/30 Insignificant 27 3-l-5 Ether-TEA 5 20 l 28 4-1-5 nCS5 5 2.3

29 4-1-6 None 2+6 0/10 11.1

30 l-l-l4 HCyTEA 5 2 23/10 8.6

Key: OH Alcohol MeOH Methanol Ether Diethyl ether From the aboveeitamples it can be seen that the enhancement in reaction rate is notobtained at the cost 20 of increased sludge formation.

Having disclosed my invention, what isto be covered by Letters Patentshould be determined not by the examples herein given, but from'theappended claims.

promoter selected from the group consistingof tributylamine,triethylamine, n-butylamine, tetraethylammonium hydroxide, and pyridineto said medium, injecting said gaseous hydrogen chloride into saidmedium at a temperature between about 20 and about 100 F. and a pressurebetween about 0.5 and 100psig, 40 and recovering a tertiary alkylchloride from said reaction medium.

2. A process as defined by claim 1 wherein said reaction medium containsaqueous hydrochloric acid.

3. A process as defined by claim 1 wherein said amine is tributylamine.

4. A process as defined by claim 1 wherein said amine is triethylamine.

5. A process as defined by claim 1 wherein said amine is n-butylamine.

6. A process as defined by claim 1 wherein said amine istetraethylammonium hydroxide.

7. A process as defined by claim,1l wherein said amine ispyridine.

8. A process as defined by claim 1 wherein said ter- 9. A process forthe preparation of a tertiary alkyl chloride by the chlorination of atertiary alcohol which comprises preparing a liquid reaction mediumcontainingsaid alcohol, from about 20 to about 50 weight percent ofbenzene, and from about 0 .3 to about 15 weight percent oftributylamine; introducing gaseous hydro gen chloride into said reactionmedium while maintaining said medium at. a temperature between about 20and about F. and at a pressure between about 0.5 and about 100 psig, andrecovering a tertiary alkyl chloride from said reaction medium.

10. A process as defined by claim 9 wherein an aqueous hydrochloric acidsolution is added to said reaction medium prior to the introduction ofsaid gaseous hydrogen chloride.-

11. A process for the preparation of a tertiary alkyl chloride by thechlorination of a tertiary alcohol which comprisespreparing a liquidreaction medium containing said alcohol, from about 20 to about 50weight percent of carbon tetrachloride, and from about 0.3 to about 15weight percent of tributylamine; introducing gaseous hydrogen chlorideinto said reaction medium while maintaining said medium at a temperaturebetween about 20 and about 100 F. and a pressure between about 0.5 andabout 100 psig, and recovering a tertiary alkyl chloride from saidreaction medium.

112. A process as defined by claim 11 wherein an aqueous hydrochloricacid solution is added to said reaction medium prior to the introductionof said gaseous hydrogen chloride.

1. IN THE LIQUID PHASE CHLORINATION OF A TERTIARY ALCHOL TO PRODUCE THECORRESPONDING TERTIARY ALKYL CHLORIDE BY INJECTING GASEOUS HYDROGENCHLORIDE INTO A LIQUID REACTION MEDIUM CONTAINING SAID ALCOHOL AND FROMABOUT 20 TO ABOUT 50 WEIGHT PERCENT OF A HYDROCARBON SOLVENT WHICH BOILSIN THE RANGE BETWEEN ABOUT 75* AND ABOUT 360*F. AND IS AN INERT LIQUIDAT THE CHLORINATION TEMPERATURE, THE IMPROVEMENT WHICH COMPRISES ADDINGFROM ABOUT 0.3 TO ABOUT 15 WEIGHT PERCENT OF AN AMINE PROMOTER SELECTEDFROM THE GROUP CONSISTING OF TRIBUTYLAMINE, TRIETHYLAMINE, N-BUTYLAMINE,TETRAETHYLANNONIUM HYDROXIDE, AND PYRIDINE TO SAID MEDIUM, INJECTINGSAID GASEOUS HYDROGEN CHLORIDE INTO SAID MEDIUM AT A TEMPERATURE BETWEENABOUT 20* AND ABOUT 100*F. AND A PRESSURE BETWEEN ABOUT 0.5 AND 100PSIG, AND RECOVERING A TERTIARY ALKYL CHLORIDE FROM SAID REACTIONMEDIUM.
 2. A process as defined by claim 1 wherein said reaction mediumcontains aqueous hydrochloric acid.
 3. A process as defined by claim 1wherein said amine is tributylamine.
 4. A process as defined by claim 1wherein said amine is triethylamine.
 5. A process as defined by claim 1wherein said amine is n-butylamine.
 6. A process as defined by claim 1wherein said amine is tetraethylammonium hydroxide.
 7. A process asdefined by claim 1 wherein said amine is pyridine.
 8. A process asdefined by claim 1 wherein said tertiary alcohol contains from seven to28 carbon atoms per molecule.
 9. A process for the preparation of atertiary alkyl chloride by the chlorination of a tertiary alcohol whichcomprises preparing a liquid reaction medium containing said alcohol,from about 20 to about 50 weight percent of benzene, and from about 0.3to about 15 weight percent of tributylamine; introducing gaseoushydrogen chlOride into said reaction medium while maintaining saidmedium at a temperature between about 20* and about 100* F. and at apressure between about 0.5 and about 100 psig, and recovering a tertiaryalkyl chloride from said reaction medium.
 10. A process as defined byclaim 9 wherein an aqueous hydrochloric acid solution is added to saidreaction medium prior to the introduction of said gaseous hydrogenchloride.
 11. A process for the preparation of a tertiary alkyl chlorideby the chlorination of a tertiary alcohol which comprises preparing aliquid reaction medium containing said alcohol, from about 20 to about50 weight percent of carbon tetrachloride, and from about 0.3 to about15 weight percent of tributylamine; introducing gaseous hydrogenchloride into said reaction medium while maintaining said medium at atemperature between about 20* and about 100* F. and a pressure betweenabout 0.5 and about 100 psig, and recovering a tertiary alkyl chloridefrom said reaction medium.
 12. A process as defined by claim 11 whereinan aqueous hydrochloric acid solution is added to said reaction mediumprior to the introduction of said gaseous hydrogen chloride.